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Investments - Change in investments (Details) $ in Millions, $ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Nov. 30, 2020 USD ($) | Nov. 25, 2020 CAD ($) | Nov. 25, 2020 USD ($) | Dec. 31, 2020 CAD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2018 CAD ($)
Change In Investments [Roll Forward] |  |  |  |  |  |
Equity income |  |  |  | $ 1 | $ 0 | $ 0
Change in foreign exchange rates |  |  |  | 17 | (15) | $ (15)
Consolidated structured entities [member] |  |  |  |  |  |
Change In Investments [Roll Forward] |  |  |  |  |  |
Balance, Dec. 31, 2019 |  |  |  | 0 |  |
Contributions |  |  |  | 102 |  |
Equity income |  |  |  | 1 |  |
Change in foreign exchange rates |  |  |  | (3) |  |
Balance, Dec. 31, 2020 |  |  |  | 100 | 0 |
Skookumchuck |  |  |  |  |  |
Change In Investments [Roll Forward] |  |  |  |  |  |
Contributions |  | $ 86 | $ 66 |  |  |
EMG International, LLC |  |  |  |  |  |
Change In Investments [Roll Forward] |  |  |  |  |  |
Contributions | $ 12 |  |  |  |  |
SP Skookumchuck Investment, LLC |  |  |  |  |  |
Change In Investments [Roll Forward] |  |  |  |  |  |
Balance, Dec. 31, 2019 |  |  |  | 0 |  |
Contributions |  |  |  | 86 |  |
Equity income |  |  |  | 1 |  |
Change in foreign exchange rates |  |  |  | (2) |  |
Balance, Dec. 31, 2020 |  |  |  | 85 | 0 |
EMG International, LLC |  |  |  |  |  |
Change In Investments [Roll Forward] |  |  |  |  |  |
Balance, Dec. 31, 2019 |  |  |  | 0 |  |
Contributions |  |  |  | 16 |  |
Equity income |  |  |  | 0 |  |
Change in foreign exchange rates |  |  |  | (1) |  |
Balance, Dec. 31, 2020 |  |  |  | $ 15 | $ 0 |

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- Definition The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2019-01-01 -Section A Statement of cash flows for an entity other than a financial institution -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2019-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 21 -IssueDate 2019-01-01 -Paragraph 52 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2019-en-r&anchor=para_52_a&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of investments in associates accounted for using the equity method. [Refer: Associates [member]; Investments accounted for using equity method] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The cash outflow to acquire interests in joint ventures (other than payments for those instruments considered to be cash equivalents or those held for dealing or trading purposes), classified as investing activities. [Refer: Joint ventures [member]] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2019-01-01 -Paragraph 16 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2019-en-r&anchor=para_16_c&doctype=Standard -URIDate 2019-03-27 + Details
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